Continuous foam-producing method and apparatus



Nov. 11, 1930. P. w. PRUTZMAN 1,781,293

CONTINUOUS FOAM PRODUCING METHOD AND APPARATUS Filed Sept. 28, 192? Qua/2* M Patented Nov. 11, 1930 PATENT OFFICE PAUL W, PRUTZMAN, LOS ANGELES, CALIFORNIA CONTINUOUS FOAM-PRODUCIN G METHOD AND APPARATUS Application filed September 28, 1927. Serial No. 222,567.

The art of extinguishing fires in general, and particularly oil fires, by means of Foamite or Firefoam is very well known and understood. It consists in bringing together solutions of (a) aluminum sulfate and (7)) hydrogen sodium carbonate-and a substance having the property of increasing the surface tension of aqueous liquids, such for instance as glue or licorice. By the admixture of said 10 solutions in proper strengths and proportions a very dense and tenacious foam is produced which, as it consists mainly of water and is suificiently light to float on oil, is a highly efficacious and valuable agent for extinguishing fires.

It has heretofore been the custom either to prepare the solutions in advance and to store them until needed, distributing them at such times by means of duplicate lines to such parts of a plant (as, an oil refinery) as may require protection, or to store small quantities of the solutions in pressure tanks mounted on wheels. which can be taken to the seat of the fire. The first system is disadvantageous in that the required investment is very heavy, and more particularly in that the capacities of the tanks are necessarily limited and the time required for recharging them quite extended. It has often occurred that these tanks have become exhausted in the course of a stubborn fire, and that before they could be refilled the fire had gotten quite out of hand. The second system is disadvantageous in that the output of foam from the largest unit 5 which is actually port-able is so trifling that these portable tank units can take care of only the smallest fires.

An object of my invention is to provide a 40 cheap and effective means for the continuous production of solutions of the foam chemicals from their dry salts, thus doing away with the requirement for any storage whatever of solution and avoiding a possible failure of 5 solution supply during the course of a fire. The original supply of foam chemicals is large as compared to the supply'in solution tanks, which are filled mainly with water, and the renewal of this supply may be made continuously or intermittently without in the slightest degree interrupting the continuity of delivery of solution by the apparatus.

In one adaptation of my invention it may be used in connection with a duplicated system of existing distributing lines. A further and still more important object of my invention is to provide a simple and effective portable apparatus which can be taken to the seat of the fire and there, being supplied with water and bulk chemicals, will supply for an indefinite period separate streams of the two solutions, which can be separately conducted to the actual fire and there intermixed in any preferred type of mixing head. The advantages of my improved foam producing apparatus will be most fully realized if the solutions produced therein are mixed in the misting spray nozzle described and claimed by James A. McCracken in his application filed June 24th, 1927, under Serial No. 201,134 or in the Fire-foam spreader head described and claimed by James A. McCracken in his application filed July 6th, 1927 under Serial No. 203,766. It should, however, be understood that my invention is not restricted to use with any particular means of intermixing solutions for the production of a fire-extinguishing foam.

A further, and perhaps the most important object of my invention, is to provide a strict 1y automatic means which, when supplied with water under pressure, will continuously deliver streams of solution exactly proportioned as to both quantity and strength, thus producing the maximum quantity of the most efficient foam, and this without any regulation or control except that which may be exercised over the rate of solution delivery,

which may be varied at will over a wide range. i

These advantages and the manner in which they are attained will be evident from the following description of the attached drawing, which diagrammatically illustrates in vertical section a preferred complete embodiment of my invention.

Referring to the drawing, 1 is a tank for dissolving the aluminum sulfate (hereinafter referred to as alum), 2 is a tank for dissolving the hydrogen sodium carbonate (hereinafter referred to as soda), 3 is a tank for holding a diluted commercial solution of extract of licorice, and 4 is a tank for holding water. Tanks 1 and 2 are divided part way down by the partition plates 5 and 6, which extend from side to side of each tank, the spaces thus partitioned off being substantially closed at the top by the plates 7 and 8. The purpose of these plates is merely to keep the dry chemicals supplied to the tanks from dropping onto the fioat valve, and they may be omitted if preferred. The space in these tanks up to about the level indicated by the dotted lines 9 and 10 is to be kept filled with t'lie said chemicals in powdered form.

Tanks 1 and .2 are kept filled with water up to the levels indicated at 11 and 12 by means of ordinary float-valves 13 and 14, this water being supplied under any convenient pressure by means of pipes 15 and 16 communicating with a supply pipe 17 This pipe terminates in a hose union 18 by which the supply pipe may be coupled to a fire hydrant or other source of water supply.

The float valves 13 and 14 communicate with down-pipes 19 and 20 which are bent out to the diametric center of tanks 1 and 2 and carried to a point close to the bottom thereof. These pipes may terminate in a rose spray nozzle or they may be made to discharge beneath the perforated plates 21 and 22 by which the water as it rises is divided into a number of streams.

23 and 24 are pumps of any suitable pattern, preferably rotary gear pumps, which should be coupled together so as to rotate at the same speed. They may be driven, as by the pulley 25, from a common source of power not shown, which source may, if the apparatus is designed to be portable, be the engine driving the truck on which the apparatus is mounted.

Tank 4 is kept filled with water to the level 26 by means of the ordinary float valve 27, which also communicates with water supply line 17 through a branch line 28.

he suction opening 29 of pump 23 communicates with a line 31-31 which takes suction on tank 1 at the point indicated at 32 and on tank 4 at the point indicated at 33. In these two suction lines are placed the orifice plates 34 and 35, the purpose of which will later be described.

The suction opening 36 of pump 24 communicates with a pipe 37 which takes suction on tank 2 at the point indicated at'38 through the branch line 39 and also on tank 3 at the point 40 through the branch line 41. In these two branch lines 30 and 41 are placed the orifice plates 42 and 43.

The rectangle 44 shown in the drawing between tanks 3 and 4 is one of a plurality of spacing members by which tank 3 is supported on tank 4. Both of these tanks are open at the top, and a more refined means of sup orting and spacing them may be used if pre erred.

The discharges from pumps 23 and 24 are taken through risers 46 and 47 which terminate in the hose couplings 48 and 49. To

these couplings may be connected separate lines for conducting the solutions to the seat of the fire. For short distances these separate discharge lines may be of hose only, for greater distances of hose and iron pipe. The two lines may, if preferred, be brought together into one line, preferably of greater diameter, say fifty feet from their final point of discharge, but pumping the foam thus produced for a materially greater distance or through a small line is highly disadvanta geous because of the breaking down of foam which follows therefrom.

As illustrated in the drawing the entire apparatus is shown as mounted on the bed of a truck generallyindicated at 50. It

will of course be obvious that the device may be constructed in various sizes, for use as a stationary plant or as a large or small portable plant.

As it is essential to the proper functioning of my device that the suction lift of the two pumps be kept approximately equal, and as two identical pumps operating under exactly the same conditions will ordinarily have a different amount of slip, I have provided the by-passes 51 and 52 between' the discharge side and the suction sideof each pump, these by-passes being controlled by valves 53 and 54 and the suction lift read on the vacuum gauges 55 and 56. By cracking the by-pass valve on whichever pump shows the higher lift the excess slip of the opposite pump may be offset and the two suction lifts brought into unison, but this valve opening may require to be readjusted if the speed of the two pumps is materially altered, as to change the rate of total deliverv. Such change in speed, however, will not change the relative delivery of the orifice plates. It will be noted that these by-passes must not be connected behind any of the orifice plates but must be brought in close to the suction of the pump.

Before describing the operation of my apparatus it should be stated that the fire extinguishing foam is produced by the admixture of the chemicals above named (alum, soda and a stabilizer such as licorice) together with a quantity of water which. has been shown by experience to produce the most desirable quality and quantity of foam. Using this total quantity of water, and the correct proportion of each chemical, it makes no particular difierence how the water is distributed between the three solutions, provided only that enough water is used with any one chemical tokeep it in complete solution. However, when using an outside-mixmg head, such as those above named, it Is preferable that the solutions reach the mixing head in two streams of substantially equal volume and pressure, as the heads are thus caused to function mostelficiently as mixing and distributing agents.

The ratio of alum to soda is determined by adefinite chemical reaction and is a fixed ratio. The ratio of stabilizer to volume of solution has also been fairly well fixed by repeated experiment. water which may be incorporated in the foam is a matter not only of opinion but also depends to a greatextent on the manner in which the foam is produced and transported. In other words, the water is a diluent of the foam, and if the latter can be prevented from breaking down and resolving itself into its constituents during the period intervening between the manufacture of the original solutions and the application of the foam to fire, a smaller proportion of the reagents will be required to produce unit volume of foam, and by consequence the foam will be lighter and more certain to float on burning oil.

The proportions of chemicals which I pre fer to use are therefore less than is considered desirable in standard practice, this reduction in consumption of chemicals being one of the advantages of my novel method of making and using the solutions. It will be understood, however, that my invention is not limited to the proportions stated, which are given by way of illustration only, nor even to the particular chemicals stated, but only to such chemicals and such proportions as will produce a satisfactory fire extin uishin foam.

The proportions of chemicals whic I prefer to use for each 100 gallons of total solu tion are as follows :alum (commercial aluminum sulfate, containing 18 molecules of water) Bounds; soda (commercial sodium bicarbonate)35 pounds; extract of licorice (calculated to the dry form)-5 pounds. The commercial stabilizers such as licorice come onto the market as a viscous liquid or paste containing approximately one part by weight of the dry extract with two parts by weight of water, and as this paste is too thick to measure accurately by my method I prefer to dilute it with three parts of water prior to use.

The rationale of my invention is to first produce saturated solutions of the two salts, alum and soda, these saturated solutions having, within a reasonable temperature range, a practically constant composition, so

that a definite weight of each salt may be ob tained by measuring out a definite quantity of the solution. These two solutions are kept separate. I then add to one or the other of these'solutions the requisite quantity of the stabilizer solution, this addition being made by preference to the soda solution. Finally, I add to one or the other, or both, of the said solutions, the quantity of water required to But the quantity of.

make up the solution to the total volume. It will be understood that in actual operation these steps are not taken in order, but are continuous and coincident, the measurement of the four liquids being made by drawing them, at an equalized pressure difference, through orifices of predetermined sizes.

As an illustration of the manner in which the respective quantities of the four liquids are calculated, I may use the proportions of reagents to volume of solution above given, the quantities for other proportions being figured in exactly the same manner.

At ap roximately F., 100 parts by weight 0 water dissolve 107 parts by weight of alum, producing 207 parts by weight of y a saturated solution having the specific gravi 'i" At the same temperature parts by weight of water dissolve 11 parts by Weight of soda, roducing 111 parts by weight of a saturate solution having the specific gravity"1.03.

1 00 parts byweight of commercial licorice paste contains approximately 33 parts ghy weight of dry extract of licorice and 67 parts by weight of water, the specific gravity of the paste bein approximately 1.50.

From t e above figures we derive the weights and volumes required to produce100 gallons total solution.

Gallons 60# alum and 56# Water yield 1164.1:

sat. sol 9 0 35# soda and 318# water yield 353.11:

sat. sol 41.2 5# licorice dry-15:1,: commercial paste 1.2 Water added to licorice aste, 3 volumes 3.6 Water required to comp ete quantity--- 45.0

If we bring together the requisite quantity of alum solution and the water required to complete the volume we have 54.0 gallons of diluted alum solution. If we likewise bring together the soda solution and the diluted licorice we have 46.0 gallons of soda solution containing enou h excess water (comprised in the diluted licorice) to safely maintain the soda in solution: The two solutions so compounded reach the mixing head in proportions close enough to the nominal 50-50 to ensure proper action of the head.

The four orifice plates will therefore have to pass the following relative quantities: plate 34, saturated alum solution, 9.0-gallons per minute; plate 35, water, 45.0 gallons per minute; plate 42, saturated soda solution, 41.2 gallons per minute; plate 43, diluted licorice solution, 4.8 gallons per minute. Plates passing these relative quantities at uniform pressure difference may readily be constructed, though they can be only roughly calculated and should be finished by reaming and trial. If it is anticipated that the engine will work over any wide variation of delivery rate the material of the plates should Rice be thin, to permit them toretain their ratio of delivery over a. wide range of pressure difference.

Inoperatingmyinventionthesimpleststeps are required. Tanks 1 and 2 are charged to the preferred height, as to the level indicated by the dotted lines 9 and 10, with the dry chemicals, alum in tank 1 and soda in tank 2. On account of the weight of a full charge the apparatus may be taken to the fire say onequarter charged, enabling it to be put into immediate operation on arrival, and the balance of the charge made up thereafter. A hose connection is then made to the union 18 and the stop valve 59 in the water line 17 opened, allowingtanks 1, 2 and 4 to fill.

Tank 3 is meanwhile filled with diluted licorice solution and the discharge lines connected to pump discharges 48 and 49.

When the level of solution (which will be saturated, owing to the contact of water with an excess of salt during its upward passagev through tanks 1 and 2) reaches the outflow openings 32 and 38, the pump suctions Wlll flood and the pumps may then be started, delivery of solutions at approximate strength then beginning. As soon as the pumps come up to the proper speed the suction lifts should be balanced by adjusting one or the other of the by-pass valves 53 and 54, as before described. This being done, the apparatus requires no further attention for an indefinite period except to see that the pump s eed is so regulated as to give the desired yleld of solutions, that tanks 1 and 2 are kept filled with their appropriate chemicals, which may be shovelled in as needed, and that tank 3 is supplied with licorice solution.

As illustrating the various sizes of the various parts making up this apparatus and without limiting myself to such sizes or proportions, I may say that if dissolving tanks 1 and 2 are made say 2 6" in diameter and 5' 6" high they will charge about 1500# each of dry salt, and will deliver solutions at a total rate of 100 gallons per minute (equal to 1,000 gallons of foam) for say 20 minutes without recharging and without running the supply of salt down to the point where the solutions might not be entirely saturated. The licorice solution tank should be of about the same capacity (200 gallons) while the water tank 4, acting merely as a pressure equalizer, may be of any size desired down to 40 or 50 gallons.

An apparatus in this size will be limited in capacity only by the relatively low solution rate of the soda, and may be depended on for a steady supply up to 400 or 500 gallons per minute, equivalent to 4,000 to 5,000 gallons of foam. Such quantities will care for a fire of the first magnitude.

' The delivery rate will depend not only on the diameter but also on the height of the solution tanks, and these may be made narrower if operating time without refilling is not an object, or may be made taller with an increase in delivery rate with some sacrifice of convenience in charging.

If preferred, the orifice plates 34, 42, 43 and 35 may each or any be replaced by a control valve or stopcock in series with a meter for liquids, by which the ratios of the various flow streams may be controlled.

It will be understood that when, in the following claims, I use the terms acid, soda and licorice, I refer respectively to aluminum sulfate (A1 (SO ,.18H O), hydrogen sodium carbonate (HNaC0 and a commercial extract of licorice, or their substantial equivalents for the purpose described.

I claim as my invention:

1. A method of simultaneously and continuously producing two dissimilar fire-foam solutions and leading them to a point of intermixture, comprising: placing in a vessel substantially open at its top a mass of powdered alum; placing in a similar vessel a mass of powdered soda; feeding water upwardly through each said mass to produce a substantially saturated solution of the powder contained in said vessel; maintaining a quantity of undissolved powder underlying a layer of said saturated solution in each said vessel; separately and continuously drawing streams of said solution by suction from said layers of solution through orifices adjusted to pass said solutions in predetermined proportions; continuously drawing into one of said streams of solution a flow stream of water through an orifice adjusted topass said water in a predetermined proportion, and separately forcing said solutions to a point of intermixture thereof.

2. A method of simultaneously and continuously producing two dissimilar fire-foam solution and leading them to apoint of intermixture, comprising: placing in a vessel substantially open'a-t its top a mass of powdered alum; placing in a similar vessel a mass of powdered soda; feeding water upwardly through each said mass to produce a substantially saturated solution of the powder contained in said vessel; maintaining a quantity of undissolved powder underlying a layer of said saturated solution in each said vessel; separately and continuously drawing streams of said solution by suction from said layers of solution through orifices til) the solutions so withdrawn.

of intermixture, comprising: placing in a vessel substantially open at its top a mass of powdered alum; placin in a similar Yessel a mass of powdered so a; feeding water upwardly through each said mass to produce a. substantially saturated solution of the powder contained in said vessel; maintaining a quantity of undissolved powder underlying a layer of said saturated solution in each said vessel; separately and continuously drawing streams of said solutions by suction from said layers of solution through orifices adjusted to pass said solutions in predetermined proportions, and separately forcing said solutions to a point of intermixture thereof.

4:. An apparatus for simultaneously and continuously producing two dissimilar firefoam solutions and leading them to a point of intermixture, comprisingzvt wo tanks having substantially open tops, adapted to con tain masses of powdered'alum and powdered soda respectively; means for admitting flowstreams of water beneath said masses for separately producing solutions thereof; automatic means for maintaining a substantially constant depth of liquid in each tank; pumping means for separately withdrawing from said tanks, under suction; flow-streams of the solutions so produced and for forcing said flow-streams to a point of inter-mixture thereof; orifice means on the suction side of said pumping means for predetermining and controlling the relative proportions of the solutions so withdrawn, and orifice means for admitting a predetermined proportion of an aqueous liquid into one of said streams.

5. An apparatus for simultaneously and continuously producing two dissimilar firefoam solutions and leading them to a point of intermixture, comprising: two tanks having substantially open tops adapted to contain masses of powdered alum and powdered soda respectively; means for admitting flow streams of water beneath said masses for separately producing solution thereof; means for maintaining a substantially constant depth of liquid in each tank; pumping means for separately withdrawing from said tanks, under suction, flow-streams of the solutions so produced and for forcing said flow-streams to a point of intermixture thereof, and orifice means on the suction side of said pumping means for predetennining and controlling the relative proportions of In. witness that I claim the foregoing I have hereunto subscribed my name this 20th day of September, 1927.

PAUL lV. PRUTZMAN. 

